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package com.mycompany.programingexam2_calebfontenot;

/**
 *
 * @author ar114
 */
public class ProgramingExam2_CalebFontenot<T> {

    Node<T> head;
    Node<T> tail;

    class Node<T> {

        T t;
        Node<T> l;
        Node<T> r;
    }

    public T removeAt(int pos) {
        if (pos < 0 || pos > size() - 1) {
            throw new IndexOutOfBoundsException();
        }

        //list is empty
        if (size() == 0) {
            throw new RuntimeException("The list empty.");
        }
        T returnT = null;

        if (pos == 0)//remove at 0
        {
            Node<T> pointer = head.r;
            returnT = (T) head.t;
            pointer.l = null;
            head = pointer;
        } else if (pos == (size() - 1))//remove at end
        {
            Node<T> pointer = tail.l.l;
            returnT = (T) tail.t;
            pointer.r = null;
            tail = pointer;
        } else//remove in the middle
        {
            // Iterate to the element position
            Node<T> pointer = head;
            for (int i = 0; i < pos - 1; ++i) {
                pointer = pointer.r;
            }
            pointer.r = pointer.r.r;
            pointer.l = pointer.r;
            returnT = (T) pointer.t;
            
        }

        return returnT;
    }

    public void clear() {
        head = tail = null;
    }

    public void addAt(T t, int pos) {
        if (pos < 0 || pos > size()) {
            throw new IndexOutOfBoundsException();
        }
        Node<T> newNode = new Node<T>();
        newNode.t = t;
        if (head == null)//list is empty
        {
            head = tail = newNode;
        } else if (pos == 0)//add at the front
        {
            newNode.r = head;
            head.l = newNode;
            head = newNode;
        } else if (pos == size())//add at the end
        {
            newNode.l = tail;
            tail.r = newNode;
            tail = newNode;
        } else//middle
        {
            Node<T> p = head;
            for (int i = 0; i < pos - 1; ++i) {
                p = p.r;
            }
            newNode.l = p;
            newNode.r = p.r;
            p.r.l = newNode;
            p.r = newNode;
        }
    }

    public int size() {
        Node<T> p = head;
        int count = 0;
        while (p != null) {
            count++;
            p = p.r;
        }
        return count;
    }

    @Override
    public String toString() {
        String s = "";
        Node<T> p = head;
        while (p != null) {
            s += p.t.toString() + " ";
            p = p.r;
        }
        return s;
    }

    public static void main(String[] args) {
        ProgramingExam2_CalebFontenot<Integer> list = new ProgramingExam2_CalebFontenot<Integer>();

        list.addAt(20, 0);
        list.addAt(10, 0);
        list.addAt(40, 2);
        list.addAt(30, 2);
        list.addAt(50, 4);
        System.out.println(list);
        System.out.println(list.removeAt(0));
        System.out.println(list);
        System.out.println(list.removeAt(2));
        System.out.println(list);

        System.out.println(list.removeAt(2));
        System.out.println(list.toString());
    }

}